twintwin10032017-01-04 21:24:31
twintwin1003, 2017-01-04 21:24:31

AES branch number?

By definition branch number 5960710c116041f6aeb36d240b72641cTaken from here (7.3.1)
Where W(a) is the weight of the vector i.e. number of nonzero vector components
AES uses a predefined matrix in the MixColumns operation . It is necessary to prove that for it (the matrix) branch number = 5.
1. In the same article (7.3.1) it is said that

the output can have at most 4 active bytes
Hence, the upper bound for the branch number is 5

It turns out that W(F(a)) maximum can be equal to 4 (why?) and W(a) = 1. Why W(a) = 1, because the number of non-zero components can be greater than 1? Or is this where you should pay attention to min()?
2. How to calculate W(F(a)), for eachdb8f7468a3784383ac02ba160ee80aba

Answer the question

In order to leave comments, you need to log in

Didn't find what you were looking for?

Ask your question

Ask a Question

731 491 924 answers to any question